language: C++11 (gcc-4.7.2)
date: 530 days 15 hours ago
link:
visibility: public 
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#include <cmath>
#include <type_traits>
 
namespace detail {
    using namespace std;
    struct dummy {};
    void isnan(dummy);
    bool isnan(float); // Just adding this declaration makes it work!
    template <typename T>
    struct is_isnan_available {
        template <typename T1>
        static decltype(isnan(T1())) test(int);
        template <typename>
        static void test(...);
 
        enum { value = !std::is_void<decltype(test<T>(0))>::value };
    };
}
 
int main() {
    return detail::is_isnan_available<float>::value;
}